The defendant, who wore a black and pink top, wiped away tears after entering her pleas.

She denied charges of theft and possessing morphine, which were accepted by the prosecution.

Adrian Keeling, prosecuting, said: “She has admitted the attempted murder by poisoning of three of her work colleagues.”

She was arrested on August 4 after police were informed that 16 people at Goldfield Court - on in their 90s - had been taken ill with food poisoning-type symptoms, including severe headaches, intense nausea and diarrhoea.

Several required hospital treatment.

The court was told today that the attempted murder charges related to her work colleagues.

The case was not opened in court and Swift was remanded in custody ahead of being sentenced on April 17.

Goldfield Court is described as ‘extra care housing’ for older people and there are 93 flats at the site.

The development includes lounges, a restaurant, a hair salon, a guest suite, an activity room and gardens for residents.

In its most recent inspection of the sheltered housing complex, independent regulator the Care Quality Commission found the site was meeting all standards.